Hot melt adhesives are adhesives which are applied molten, at elevated temperatures in the substantial absence of a solvent. The hot melt can be applied in a glue line and can form a strong, adherent bond when cooled. Hot melt adhesives are typically made by combining a thermoplastic base polymer with a variety of other additive components to produce desirable properties in the finished adhesive composition. A great deal of attention has been directed for many years to the development and the formulation of hot melt adhesives in view of the economy, safety, ease of use, and applicability of hot melt adhesive technology.
Hot melt adhesives can be made from a variety of thermoplastic base polymers including ethylene-vinyl acetate polymers, atactic polypropylene polymers, acrylic polymers, vinyl pyrrolidone polymers, polyalkylene-oxazoline polymers, natural and synthetic rubbers such as KRATON, KRATON G and others, etc. Such hot melt adhesives can be pressure sensitive, and can be used on a variety of natural and synthetic substrates. The adhesives can be either insoluble in water or partially or fully soluble in water, and can be water actuated.
The successful formulation of a variety of hot melt adhesives with various properties requires a number of multi-functional adhesive components. Many adhesive components currently available for use in adhesive formulation can be used in combination to provide an adhesive of high quality. Certain adhesive applications have no fully successful adhesive. Fluorocarbon bonded materials, for example, are well known for resistance to formation of strong bonds with current adhesives. New materials in packaging are constantly being developed which require adhesives that are useable with the new materials.
A constant search is underway for new adhesive additive compositions for use in adhesive formulations that can impart novel properties to adhesives, can increase the compatibility of adhesive components, can adhere to fluorocarbons and other new materials and can reduce the cost of current adhesive formulations. Accordingly a continuing need exists for improved hot melt adhesive additive components.